[Eric] understanding eric4 slowness

[Phil Thompson]

On Friday 13 April 2007 7:01 pm, Detlev Offenbach wrote:
> On Freitag, 13. April 2007, Andreas Pakulat wrote:
> > On 13.04.07 19:26:28, Detlev Offenbach wrote:
> > > On Mittwoch, 11. April 2007, Andreas Pakulat wrote:
> > > > c) How do I do performance tests on eric4? I tried the profile
> > > > project option in eric3 but after the splash screen vanishes nothing
> > > > seems to happen.
> > >
> > > Over here it took some time to show up on the first run.
> >
> > I'll try that again some time.
> >
> > > > All in all eric3 seems to be much faster than eric4.
> > >
> > > That is what I observed as well. However, I was not able to find the
> > > real cause. All in all I have the impression, that Qt4 is slower than
> > > Qt3. I have observed this with other (pure) Qt applications as well
> > > (both at work and at home, both on Linux and on win32). I got the
> > > impression, that the problem is worse on Linux.
> >
> > Hmm, I don't think I have a Qt4 app with a larger model, however I do
> > have experience with KDE4 and at least their filesystem-model is pretty
> > fast. So I'm not so 100% sure its just the Qt4 model/view stuff, it may
> > still be related to how the models are implemented. Anyway, I'll try to
> > get some profiling data and see what it can tell me...
> >
> > Andreas
>
> It might not really be the model/view stuff. I have the impression it is
> painting the data to the screen. If you load a really huge file in
> QScintilla2 (e.g. ViewManager.py or UserInterface.py) and enter some text
> at the beginning of the file, you shouldn't type too fast or you'll lose
> some keystrokes. This is just an example. I have seen slow paintings in
> various areas. As I said, this was observed in other Qt4 applications as
> well.

It could be painting or it could be font handling. Scintilla renders the whole 
of a document when word wrap is enabled - so it knows how many lines there 
are. I don't think you should notice problems if word wrap is disabled.

Phil